System, method and apparatus for use of dynamically variable compressor delay in thermostat to reduce energy consumption

ABSTRACT

Systems and methods are disclosed for reducing the usage of a ventilation system. For example, one or more of the exemplary systems comprise a thermostatic controller that has at least two settings for the delay occurring between turning the ventilation system off and then turning the system back on. One setting being for a first interval and at least a second setting for a second interval that is longer than the first interval. A processor is in communication with the thermostatic controller and is configured to evaluate one or more parameters including at least the temperature outside the structure conditioned by the ventilation system. The processor is further configured to determine whether to adopt the first interval or the second interval based upon the values of the parameters.

CROSS-REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet, or any correction thereto,are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND OF THE INVENTION Field of the Invention

Central heating of buildings dates to ancient Roman times. Control oftheir systems consisted of adding fuel to the fire or extinguishing it.The use of forced air systems for central heating began roughly at thebeginning of the 20^(th) century. Once easily controllable energysources such as heating oil, natural gas and electrical resistance wereemployed to heat the circulated oil, means for more accuratelycontrolling the cycling of the heat source became both possible andnecessary.

The first mechanical means for regulating room temperature by sensingtemperature and automatically adjusting date from the late 19^(th)century. These devices evolved into the simple bi-metallic devices thatbecame popular in the 1950s, such as the iconic round Honeywellthermostats that are still available today.

These thermostats sense temperature changes by using a coiled springthat is composed of a sandwich of two different metals with differentthermal coefficients of expansion, which thereby causes the coil to movewith temperature changes. The center of the coil is generally fixed; thefree end of the spring moves one way when it gets warmer and the otherwhen it gets colder. The movement of the free end of the spring is usedto open and close the circuit that turns on and off the HVAC system. Inearly versions of this type of thermostat, the electrical switch wasoften in the form of liquid mercury in a glass tube: when theelectrically conductive mercury flowed to one end of the tube, ittouched a wire and completed the circuit; when the spring tilted thetube, it flowed the other way so that the mercury no longer contactedthe wire, thus breaking the circuit.

One salutary effect of the use of such switches was that the weight ofthe mercury in the tube added physical inertia to the temperaturesensing mechanism, as it has been shown that rapid cycling of HVACsystems is both annoying to occupants and more stressful to themechanical systems than less frequent cycling is. Thus as environmentalconcerns about mercury grew in recent years, manufacturers dispensedwith the mercury switches and began using magnets to force the contactsto remain closed until changing temperatures had put sufficient tensioninto the bimetallic spring to overcome the magnetic closure. As thiseffect became better understood and was designed into thermostats, itbecame a standard design feature. The hystereses band or dead zone isnow commonly designed to hold the desired setpoint within a range of+/−1 degree Fahrenheit. So, for example, if the heating setpoint is 68degrees F., the furnace will turn on when the inside temperature assensed by the thermostat falls to 67 degrees F., and will turn off againwhen the inside temperature as sensed by the thermostat reaches 69degrees F. Thus the inside temperature is allowed to oscillate within arange of two degrees F.

When residential refrigerant-based air conditioners became widelyavailable in the 1950s, the same kinds of thermostats were used tocontrol them as well. The need for a means to preventing rapid cyclingis even more important for refrigerant-based systems is even morecritical because there is a risk of significant physical damage to acompressor if it is turned on too soon after being turned off—if therefrigerant inside the compressor is still in liquid (and thusuncompressable) form when the compressor restarts, expensive mechanicalfailures are possible.

Electronic thermostats have been available for more than 20 years. Manyof these are also programmable. In general, these thermostats no longeruse mechanical systems to sense temperature, relying instead onelectrical devices such as thermistors or thermal diodes. Switching ofthe HVAC system is accomplished with solenoids or relays triggered bylogic circuits in microprocessors. With such systems, adjustability ofthe hysteresis band is relatively simple, at least in theory. However,most systems do not allow direct access to this parameter. And thehysteresis band only protects the system against rapid automaticcycling. The hysteresis band will not prevent a user from rapidlychanging settings, which can cause the damage discussed above.

The way most electronic systems approach this problem is to enforce, viathe electronic circuitry, a compressor delay—that is, whenever thecompressor is switched off, the thermostat prevents it from restartingfor a set interval, usual in the range of two to five minutes or so.(Some air conditioners may have an additional fail-safe delay in serieswith any circuitry in the thermostat as well.)

Many programmable thermostats include mechanical switches to allow theinstaller or user to adjust the compressor delay for the system. Butbecause it is generally expected that the installer of the system willset this parameter once based upon the requirements of the specific airconditioner being controlled, these mechanical switches are generallynot accessible to the user from outside the unit. Changing thecompressor delay generally requires disassembling the thermostat.

Academic research has shown that it is not just physical systems thathave hysteresis effects. Perceived comfort at various temperatures isnot independent of temperatures at earlier points in time. Humans havebeen shown to be relatively insensitive to slow, gradual changes intemperature, at least within narrow ranges of a few degrees F.Conversely, people do notice rapid changes within the same narrow range.It has been shown that an appropriately shaped pattern of rampedsetpoints—varying the inside temperature by more than the normal +/−1degree F. range in specific ways—can maintain comfort with a loweraverage temperature in the case of heating, and a higher averagetemperature in the case of cooling, than is possible with constantsetpoints. Reducing average setpoints in winter and raising them inwinter can significantly reduce energy consumption. Examples of suchconcepts are discussed in U.S. patent application Ser. No. 12/498,142,which is hereby incorporated herein by reference in its entirety and isto be considered part of this specification.

One specific pattern that has been validated is (in the case of heating)to allow the temperature to drift 2 degrees below the user's chosensetpoint over an extended period of 1-2 hours, and to then revert asquickly as possible to the originally desired setpoint. Because the slowcooling is not easily perceived, but the rapid reheating is, thesubjective impression is weighted toward comfort, despite the fact thatthe average setpoint over the period of the “waveform” is 1 degree lowerthan the desired setpoint. (The pattern is inverted in the case of airconditioning.)

One approach to achieving the benefits of such a setpoint strategy is tospecifically schedule each of the planned setpoint changes required tocreate such a thermal waveform. This approach requires some combinationof significant local intelligence resident in the thermostat, a localcomputer capable of controlling the thermostat, and/or a remote servermanaging frequent setpoint changes on remote devices.

Another potential drawback to using programming changes to create suchthermal waveforms with conventional thermostats is that such devicesgenerally include a visual display that gives a readout of theprogrammed setpoint as well as the current inside temperature asmeasured by the thermostat. Many people have formed associations betweenspecific objective temperatures and subjective feelings of comfort—e.g.,the belief that they will be comfortable if it is 72 degrees insidetheir home, but uncomfortable if it is 74. These beliefs may have littlebasis in fact, or be true under certain circumstances but not underothers, because comfort depends on numerous factors beyond dry-bulbtemperature. Such factors include humidity, air movement, activitylevels, and the aforementioned hysteresis effects. One of the potentialperverse effects that can be caused by providing temperature readouts tooccupants is that a person who might otherwise feel comfortable maybecome convinced that he is not simply because the thermostat's displayshows a temperature that the occupant associates with discomfort.

It would be desirable for an HVAC control system to offer a simple wayto create asymmetrical thermal waveforms without the need for highlydetailed programming. It would also be desirable for an HVAC controlsystem to offer a means to create asymmetrical thermal waveforms withoutchanging the setpoint displayed by conventional thermostats.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an overall environment in which an embodimentof the invention may be used.

FIG. 2 shows a high-level illustration of the architecture of a networkshowing the relationship between the major elements of one embodiment ofthe subject invention.

FIG. 3 shows an embodiment of the website to be used as part of thesubject invention.

FIG. 4 shows a high-level schematic of the thermostat used as part ofthe subject invention.

FIG. 5 shows one embodiment of the database structure used as part ofthe subject invention

FIGS. 6 a and 6 b show how comparing inside temperature against outsidetemperature and other variables permits calculation of dynamicsignatures.

FIG. 7 shows a flowchart illustrating the steps required to initiate acompressor delay adjustment event.

FIGS. 8( a) through 8(c) illustrate how changes in compressor delaysettings affect HVAC cycling behavior by plotting time againsttemperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Because most HVAC systems are essentially binary systems in that theyare either ON or OFF, even the best thermostat is not capable ofmaintaining a stable temperature without variation. The use of ahysteresis band in effect creates an oscillation around the setpoint.The period of that wave form (that is, the length of time it takes tocomplete a full cycle) is determined by several factors, including thedifference between outside and inside temperatures, the thermalperformance of the structure being conditioned, and the capacity of theHVAC system. But the hysteresis band ensures that under mostcircumstances the amplitude of the waveform is roughly fixed. In otherwords, a traditional thermostat creates a temperature waveform insidethe home that has a pre-defined peak-peak variation or amplitude that itseeks to maintain (generally 2 degrees F. peak to peak). As outsidetemperatures diverge from inside temperatures, the frequency of cyclingincreases. Under mild conditions, a well-insulated home with anappropriately sized HVAC system, the period of the waveform may be aslong as an hour or more. On very cold winter days or hot summer days ina poorly insulated home with an oversized HVAC system, the period may beas short as a few minutes. Only when the conditions overwhelm the HVACsystem (generally, when it is so hot that the air conditioner cannotmaintain inside temperatures within the hysteresis band) does insidetemperature go outside the defined range of waveform amplitude, at whichpoint the system runs in open-loop mode.

Under normal conditions, the compressor delay will not materially affectthat cycling behavior. But the compressor delay, if sufficiently longrelative to the “natural” period of the system, will alter both theamplitude and the frequency of the thermal waveform. For example, if thesetpoint is 69 degrees F., and under a given set of conditions (currentoutside temperature, humidity, and solar radiation being absorbed by thehouse, outside temperature, humidity and solar radiation absorbed by thehouse in the recent past, current inside temperature, inside temperaturein the recent past, etc.) the air conditioner cycles “on” for sevenminutes in order to lower the inside temperature from 70 degrees F. to68 degrees F., then switches “off” for five minutes during which thetemperature returns to 70 degrees, a compressor delay of four minutes orless will have no effect on the cycling of the system. Assumingsteady-state conditions, the period of the “waveform” will be twelveminutes, its amplitude will be two degrees F., and the air conditionerwill be operating on a roughly 58% duty cycle.

If under the same conditions the compressor delay is increased to eightminutes, the waveform will change significantly. Because the “off”portion of the waveform is forced to last longer than the time it takesfor the temperature to reach the top of the hysteresis band, insidetemperature will rise beyond 70 degrees, thereby increasing theamplitude of the waveform as well as its period. The “on” portion of thewaveform is likely to increase in duration as well, because the airconditioner is now called upon to drive down inside temperature by morethan two degrees. However, the key is that the waveform is no longersymmetrical around the nominal 69 degree setpoint. The air conditionerstill turns off when it reaches 68 degrees. But the extended compressordelay means that the upper boundary of the waveform is higher than 70degrees. If the combination of weather conditions and extendedcompressor delay allow the inside temperature to reach 71 degrees beforethe thermostat allows the compressor to turn on again, then theeffective hysteresis band is three degrees rather than two degrees, andthe average inside temperature (assuming a symmetrical waveform) will be69.5 degrees, rather than 69. In addition, because there is a directrelationship between the average inside temperature maintained and HVACcycle times, the increase in average inside temperature (which may bethought of the effective setpoint, as opposed to the nominal setpoint)will reduce NC cycling, and thus energy use. But because the lowerboundary of the hysteresis band is still below the chosen setpoint, thesubjective effect of the change is likely to be minimal.

In the air conditioning context, raising average temperatures in thisway will have two valuable benefits. First, as noted above, it canreduce energy usage with minimal effect on comfort. The second keybenefit flows from the dynamic nature of the waveform effects and therelatively ineleastic nature of electricity supply.

Air conditioning use is in many areas the largest component ofelectricity demand during the summer. On extremely hot days, demand mayexceed supply, which can result in service disruptions in the form ofblackouts and brownouts. Utilities seek to avoid such outcomes bybringing on line “peaker” power plants, which tend to be expensive tooperate and to pollute more and emit larger quantities of greenhousegases than do the generators used for base load. They also seek, whennecessary, to purchase additional supply from other sources on what iseffectively a spot market. More recently, utilities have also sought tobuy down demand by paying costumers to use less electricity duringperiods of critical demand. This process is known as demand response,and many utilities pay customers significant sums for the right to ask(or require) the customer to reduce energy usage during such peakperiods. In the case of residential air conditioning, such programsoften require that air conditioners be turned off for several hours at atime, or for setpoints to be raised significantly during such peakevents.

The invention described herein offers a simple method for dynamicallyoffering a small but meaningful demand response without significantlyaffecting comfort. Furthermore, the benefit offered will automaticallyincrease with need. During mild weather conditions, an extendedcompressor delay will have little or no effect, but will also beunnecessary. On a hot but not exceptional summer afternoon, extendingthe compressor delay will cause mild increase in average insidetemperature and a small decrease in the duty cycle of each affected HVACsystem. Such small individual changes, when averaged across a largenumber of homes, can deliver useful reductions in peak loads. Oncritical days, which are virtually without exception the hottest days,the same compressor delay that caused a small rise in temperature on themoderately hot day causes a larger rise and thus a greater demandresponse contribution on the very hot day. Thus the amount of demandresponse generated automatically increases during the conditions inwhich it is most needed.

FIG. 1 shows an example of an overall environment 100 in which anembodiment of the invention may be used. The environment 100 includes aninteractive communication network 102 with computers 104 connectedthereto. Also connected to network 102 are one or more server computers106, which store information and make the information available tocomputers 104. The network 102 allows communication between and amongthe computers 104 and 106.

Presently preferred network 102 comprises a collection of interconnectedpublic and/or private networks that are linked to together by a set ofstandard protocols to form a distributed network. While network 102 isintended to refer to what is now commonly referred to as the Internet,it is also intended to encompass variations which may be made in thefuture, including changes additions to existing standard protocols.

One popular part of the Internet is the World Wide Web. The World WideWeb contains a large number of computers 104 and servers 106, whichstore HyperText Markup Language (HTML) documents capable of displayinggraphical and textual information. HTML is a standard coding conventionand set of codes for attaching presentation and linking attributes toinformational content within documents.

The servers 106 that provide offerings on the World Wide Web aretypically called websites. A website is often defined by an Internetaddress that has an associated electronic page. Generally, an electronicpage is a document that organizes the presentation of text graphicalimages, audio and video.

In addition to the Internet, the network 102 can comprise a wide varietyof interactive communication media. For example, network 102 can includelocal area networks, interactive television networks, telephonenetworks, wireless data systems, two-way cable systems, and the like.

Network 102 can also comprise servers 106 that provide services otherthan HTML documents. Such services may include the exchange of data witha wide variety of “edge” devices, some of which may not be capable ofdisplaying web pages, but that can record, transmit and receiveinformation.

In one embodiment, computers 104 and servers 106 are conventionalcomputers that are equipped with communications hardware such as modemor a network interface card. The computers include processors such asthose sold by Intel and AMD. Other processors may also be used,including general-purpose processors, multi-chip processors, embeddedprocessors and the like.

Computers 104 can also be handheld and wireless devices such as personaldigital assistants (PDAs), cellular telephones and other devices capableof accessing the network.

Computers 104 utilize a browser configured to interact with the WorldWide Web. Such browsers may include Microsoft Explorer, Mozilla,Firefox, Opera or Safari. They may also include browsers used onhandheld and wireless devices.

The storage medium may comprise any method of storing information. Itmay comprise random access memory (RAM), electronically erasableprogrammable read only memory (EEPROM), read only memory (ROM), harddisk, floppy disk, CD-ROM, optical memory, or other method of storingdata.

Computers 104 and 106 may use an operating system such as MicrosoftWindows, Apple Mac OS, Linux, Unix or the like.

Computers 106 may include a range of devices that provide information,sound, graphics and text, and may use a variety of operating systems andsoftware optimized for distribution of content via networks.

FIG. 2 illustrates in further detail the architecture of the specificcomponents connected to network 102 showing the relationship between themajor elements of one embodiment of the subject invention. Attached tothe network are thermostats 108 and computers 104 of various users.Connected to thermostats 108 are HVAC units 110. The HVAC units may beconventional air conditioners, heat pumps, or other devices fortransferring heat into or out of a building. Each user is connected tothe servers 106 a via wired or wireless connection such as Ethernet or awireless protocol such as IEEE 802.11, a gateway or wireless accesspoint 11 that connects the computer and thermostat to the Internet via abroadband connection such as a digital subscriber line (DSL) or otherform of broadband connection to the World Wide Web. In one embodiment,thermostat management server 106 is in communication with the network102. Server 106 contains the content to be served as web pages andviewed by computers 104, as well as databases containing informationused by the servers, and applications used to remotely managethermostats 108.

In the currently preferred embodiment, the website 200 includes a numberof components accessible to the user, as shown in FIG. 3. Thosecomponents may include a means to store temperature settings 202, ameans to enter information about the user's home 204, a means to enterthe user's electricity bills 206, and means 208 to elect to enable thesubject invention.

FIG. 4 shows a high-level block diagram of thermostat 108 used as partof the subject invention. Thermostat 108 includes temperature sensingmeans 252, which may be a thermistor, thermal diode or other meanscommonly used in the design of electronic thermostats. It includes amicroprocessor 254, memory 256, a display 258, a power source 260, atleast one relay 262, which turns the HVAC system on and off in responseto a signal from the microprocessor, and contacts by which the relay isconnected to the wires that lead to the HVAC system. To allow thethermostat to communicate bi-directionally with the computer network,the thermostat also includes means 264 to connect the thermostat to alocal computer or to a wireless network. Such means could be in the formof Ethernet, wireless protocols such as IEEE 802.11, IEEE 802.15.4,Bluetooth, or other wireless protocols. The thermostat may be connectedto the computer network directly via wired or wireless Internet Protocolconnection. Alternatively, the thermostat may connect wirelessly to agateway such as an IP-to-Zigbee gateway, an IP-to-Z-wave gateway, or thelike. Where the communications means enabled include wirelesscommunication, antenna 266 will also be included. The thermostat 250 mayalso include controls 268 allowing users to change settings directly atthe thermostat, but such controls are not necessary to allow thethermostat to function. Specifically excluded from thermostat 108 shouldbe any non-overrideable means for prescribing a specific compressordelay.

The data used to generate the content delivered in the form of thewebsite and to automate control of thermostat 108 is stored on one ormore servers 106 within one or more databases. As shown in FIG. 5, theoverall database structure 300 may include temperature database 400,thermostat settings database 500, energy bill database 600, HVAChardware database 700, weather database 800, user database 900,transaction database 1000, product and service database 1100 and suchother databases as may be needed to support these and additionalfeatures.

The website will allow users of connected thermostats 108 to createpersonal accounts. Each user's account will store information indatabase 900, which tracks various attributes relative to users. Suchattributes may include the make and model of the specific HVAC equipmentin the user's home; the age and square footage of the home, the solarorientation of the home, the location of the thermostat in the home, theuser's preferred temperature settings, etc.

As shown in FIG. 3, the website 200 will permit thermostat users toperform through the web browser substantially all of the programmingfunctions traditionally performed directly at the physical thermostat,such as temperature set points, the time at which the thermostat shouldbe at each set point, etc. Preferably the website will also allow usersto accomplish more advanced tasks such as allow users to program invacation settings for times when the HVAC system may be turned off orrun at more economical settings, and set macros that will allow changingthe settings of the temperature for all periods with a single gesturesuch as a mouse click.

In addition to using the system to allow better signaling and control ofthe HVAC system, which relies primarily on communication running fromthe server to the thermostat, the bi-directional communication will alsoallow the thermostat 108 to regularly measure and send to the serverinformation about the temperature in the building. By comparing outsidetemperature, inside temperature, thermostat settings, cycling behaviorof the HVAC system, and other variables, the system will be capable ofnumerous diagnostic and controlling functions beyond those of a standardthermostat.

For example, FIG. 6 a shows a graph of inside temperature, outsidetemperature and HVAC activity for a 24 hour period. When outsidetemperature 302 increases, inside temperature 304 follows, but with somedelay because of the thermal mass of the building, unless the airconditioning 306 operates to counteract this effect. When the airconditioning turns on, the inside temperature stays constant (or risesat a much lower rate or even falls) despite the rising outsidetemperature. In this example, frequent and heavy use of the airconditioning results in only a very slight temperature increase inside othe house of 4 degrees, from 72 to 76 degrees, despite the increase inoutside temperature from 80 to 100 degrees.

FIG. 6 b shows a graph of the same house on the same day, but assumesthat the air conditioning is turned off from noon to 7 PM. As expected,the inside temperature 304 a rises with increasing outside temperatures302 for most of that period, reaching 88 degrees at 7 PM.

Because server 106 logs the temperature readings from inside each house(whether once per minute or over some other interval), as well as thetiming and duration of air conditioning cycles, database 300 willcontain a history of the thermal performance of each house. Thatperformance data will allow server 106 to calculate an effective thermalmass for each such structure—that is, the speed with the temperatureinside a given building will change in response to changes in outsidetemperature. Because the server will also log these inputs against otherinputs including time of day, humidity, etc. the server will be able topredict, at any given time on any given day, the rate at which insidetemperature should change for given inside and outside temperatures.

The ability to predict the rate of change in inside temperature in agiven house under varying conditions may be applied by in effect holdingthe desired future inside temperature as a constraint and using theability to predict the rate of change to determine when the HVAC systemmust be turned on in order to reach the desired temperature at thedesired time.

FIG. 7 shows a flowchart illustrating the steps required to initiate acompressor delay adjustment event. In step 1102, server 106 retrievesparameters such as weather conditions, the current price perkilowatt-hour of electricity, and the state of the electric grid interms of supply versus demand for the geographic area that includes agiven home. In step 1104 server 106 determines whether to instantiatethe compressor delay adjustment program for certain homes in response tothose conditions. In step 1106, server 106 determines whether a specifichome is subscribed to participate in compressor delay events. If a givenhome is eligible, then in step 1108 the server retrieves the parametersneeded to specify the compressor delay routine. These may include userpreferences, such as the weather, time of day and other conditions underwhich the homeowner has elected to permit hysteresis band changes, themaximum length of compressor delay authorized, etc. In step 1110 theappropriate compressor delay settings are determined, and in step 1112the chosen settings are communicated to the thermostat.

FIGS. 8( a) through 8(c) illustrate how changes in compressor delaysettings affect HVAC cycling behavior by plotting time againsttemperature. In FIG. 8( a), time is shown on the horizontal axis 1202,and temperature is shown on vertical axis 1204. The setpoint forthermostat 108 is 70 degrees F., which results in the cycling behaviorshown for inside temperature 1206. Because compressor delay CD1 1208 is,at approximately 3 minutes, shorter than the natural duration of acompressor off cycle Off1 1210 at approximately 6 minutes for thisparticular house under the illustrated conditions, the compressor delayhas no effect on the operation of the HVAC system. Because thehysteresis band operates so as to maintain the temperature within arange of plus or minus one degree of the setpoint, in the case of airconditioning the air conditioner will switch on when the insidetemperature reaches 71 degrees, continue operating until it reaches 69degrees, then shut off. The system will then remain off until it reaches71 degrees again, at which time it will switch on. The percentage oftime during which inside temperature is above or below the setpoint willdepend on conditions and the dynamic signature of the individual, home.Under the conditions illustrated, the average inside temperature AT11212 is roughly equal to the setpoint of 70 degrees.

FIG. 8( b) shows how with the same environmental conditions as in FIG.8( a), the cycling behavior of the inside temperature changes when thecompressor delay is longer than the natural compressor off cycle Off11210. Extended compressor delay CD2 1214 allows inside temperature 1216to climb above the range normally enforced by the hysteresis band.Because CD2 is roughly minutes, under the given conditions the insidetemperature climbs to approximately 72 degrees before the compressordelay allows the air conditioner to restart and drive the insidetemperature back down. But as before, the air conditioner shuts off whenthe inside temperature reaches 69 degrees. Thus the average temperatureis increased from AT1 1212 to AT2 1218. This change will save energy andreduce cycling because it takes less energy to maintain a higher insidetemperature with an air conditioner.

FIG. 8( c) shows how the same compressor delay can result in differentthermal cycling with different weather conditions. The greater theamount by which outside temperature exceeds inside temperature in theair conditioning context, the more rapidly the inside temperature willincrease during an off cycle, and the slower the air conditioner will beable to cool during the on cycle. Thus as compared to FIG. 8( b), whenthe inside temperature increased to roughly 72 degrees during theextended compressor delay of 8 minutes, a higher outside temperaturewill cause the inside temperature to increase faster, which results in apeak temperature of roughly 73 degrees, and in wider temperature cycling1220. The average inside temperature consequently increases from AT(2)1218 to AT(3) 1222.

It should be noted that the shape of the actual waveform will mostlikely not be sinusoidal, but for ease of illustration it is sometimesbe presented as such in the figures.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the inventions. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the inventions. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the inventions.

What is claimed is:
 1. A system for reducing the usage of a ventilationsystem comprising: a thermostatic controller having at least twosettings for the delay enforced by said thermostatic controller aftersaid thermostatic controller turns said ventilation system off prior toallowing said thermostatic controller to signal said ventilation systemto turn on again, one setting being for a first interval, and at least asecond setting for a second interval that is longer than said firstinterval; a processor in communication with said thermostaticcontroller, the processor configured to evaluate one or more parametersincluding at least the temperature outside the structure conditioned bysaid ventilation system, and to determine whether to adopt said firstinterval or said second interval based upon the values of saidparameters.